Streptococcal Invasive Disease - Group B, 2006

Three hundred sixty-one cases of group B streptococcal invasive disease (6.9 per 100,000), including 18 deaths, were reported in 2006. These cases were those in which group B Streptococcus (GBS) was isolated from a normally sterile site; seven cases of miscarriage or stillbirth in which GBS was cultured from the placenta were also reported.

Overall, 196 (54%) cases presented with bacteremia without another focus of infection. The other most common types of infection were cellulitis (15%), pneumonia (7%), osteomyelitis (6%), arthritis (5%), and meningitis (2%). The majority (78%) of cases had GBS isolated from blood only. Fifty-seven percent of cases occurred among residents of the metropolitan area. Forty-nine (14%) case-patients were infants less than 1 year of age, and 187 (52%) were 60 years of age or older.

Fifty-nine cases of infant (early-onset or late-onset) or maternal GBS disease were reported, compared to 44 cases in 2005. Twenty-five infants developed invasive disease within 6 days following birth (0.36 cases per 1,000 live births), and 21 infants became ill at 7 to 89 days of age. Ten stillbirths or spontaneous abortions were associated with 13 maternal invasive GBS infections.

From 1997 to 2006, there were 255 early-onset disease cases reported, and 13 infants died. Fifty-one infants were born at less than 37 weeks gestation and accounted for 20% of early-onset cases. Bacteremia without another focus of infection (79%) was the most common type of infection in these early-onset cases, followed by pneumonia (12%) and meningitis (7%).

The Prevention of Perinatal Group B Streptococcal Disease, Revised Guidelines published by CDC in August 2002 included the following key changes: the recommendation for universal prenatal screening of all pregnant women at 35 to 37 weeks gestation and updated prophylaxis regimens for women with penicillin allergies. In light of these revised guidelines, MDH reviewed the maternal charts for all 25 early-onset cases reported during 2006. Overall, 19 (76%) of 25 women who delivered GBS-positive infants underwent prenatal screening for GBS. Of these, eight (42%) women were positive and 10 (53%) were negative. One woman had an unknown test result. Among the six women who did not receive prenatal screening for GBS, none were screened upon admission to the hospital and prior to delivery of her infant. Among the 25 women of infants with invasive GBS disease, five (20%) received intrapartum antimicrobial prophylaxis (IAP). Two (25%) of the eight women with a positive GBS screening result received IAP. MDH continues to follow the incidence of GBS disease among infants, screening for GBS among pregnant women, and the use of IAP for GBS-positive pregnant women during labor and delivery.